In recent years, Adaptive Cruise Control (hereinafter referred to as “ACC”) has attracted attention as one of techniques for assisting in driving a vehicle (see, for example, PTL 1). ACC is a technique for acquiring the speed of the host vehicle, the speed of the preceding vehicle relative to that of the host vehicle, the distance between the host vehicle and the preceding vehicle, and the like to control the driving system and braking system of the host vehicle so that the vehicle speed and the following distance to the preceding vehicle are kept constant. For instance, when the speed of the host vehicle is high or the following distance is small, ACC actuates a brake to decelerate the host vehicle.
Such a technique can be used for a vehicle, such as a so-called tractor head, to which a trailer can be connected to reduce the burden on the driver operating such a vehicle and improve the comfort of running.